In a pneumatic self-levelling suspension system used for a land vehicle such as, typically, a large-sized bus, the moisture contained in the compressed air to be distributed from an air compressor to the pneumatic suspension units tends to deposit in the pipes and conduits leading from the air compressor to the individual suspension units. During cold seasons, the moisture thus deposited in the air feed network of a pneumatic suspension system freezes into ice in the pipes and conduits and sometimes makes the suspension system inoperable. To preclude this from occurring, it is important to remove the moisture deposit from the piping system from time to time but, for this purpose, experienced, time-consuming servicing of the pipes and conduits is indispensable. In order to dispense with such manual servicing, it has been proposed to install an automatic air dehumidifier unit between the air compressor and the suspension units of a pneumatic suspension system. The air dehumidifier unit has incorporated therein a body of regenerative desiccative chemical composition such as, for example, silica gel and is capable of automatically dehumidifying the compressed air passed therethrough. A problem has however been encountered in such a piping system because the desiccative chemical composition in the dehumidifier unit becomes inactive unless the dehumidifier unit is not serviced to regenerate the composition at certain regular intervals. The present invention contemplates elimination of such a problem encountered in a pneumatic self-levelling suspension system having incorporated therein an air dehumidifier unit using a regenerable desiccative chemical composition such as silica gel.
It is, accordingly, a prime object of the present invention to provide an arrangement for automatically regenerating the regenerative desiccative chemical composition in an air dehumidifier unit provided in the air feed network of a pneumatically or hydropneumatically operated, self-levelling suspension system for a land vehicle such as a large-sized bus.